1. Field of the Invention
The present invention relates to a cryptographic device for fast session switching, and more particularly, to a cryptographic device using a block cipher algorithm and capable of rapidly performing session switching.
2. Discussion of Related Art
When a session is switched while a block cipher algorithm is performed, an initialization vector value of the previous session must be stored in a safe memory area, and a cryptographic function must be reset using a session key, initialization vector, management mode, etc., of a new session. Here, the successive operations of storing information on a previous session and resetting a cryptographic function for a new session are referred to as session switch operations.
FIG. 1 is a block diagram of a conventional cryptographic device.
Referring to FIG. 1, conventional cryptographic devices are mostly for general purpose, in which encryption/decryption functions are implemented by a dedicated chip 140. In general, a Central Processing Unit (CPU) 110 takes charge of the session switch operations in the cryptographic device. However, a data bus size of a CPU is smaller than a block size and key size of a block cipher algorithm. Thus, the CPU 110 must access a memory 120 or an Input/Output (I/O) interface 130 several times for session switching. Consequently, the conventional cryptographic device has a problem in that delay time caused by the access operation of the CPU in a session switching process deteriorates overall speed and performance.